Castable refractory composition

ABSTRACT

A castable refractory composition may include from 5% to 95% by weight of alumina, aluminosilicate, or mixtures thereof; up to 70% by weight silicon carbide; up to 10% by weight carbon; from 0.1% to 5% by weight alkaline earth metal oxide and/or hydroxide; and from 0.1% to 5% by weight of silica having a surface area of at least about 10 m 2 /g. The refractory composition may further include no more than 0.5% by weight of cementitious binder, and the refractory composition may not release a significant amount of hydrogen gas upon addition of water. The refractory composition may set on addition of water. An installable refractory lining may be formed using the composition and a method including at least one of casting, self-flowing, wet shotcreeting, rodding, cast-vibrating, spraying, conventional dry gunning, or high density gunning the castable refractory composition, and setting and drying the composition.

CLAIM FOR PRIORITY

This application is a U.S. national phase entry under 35 U.S.C. §371from PCT International Application No. PCT/EP2012/066902, filed Aug. 30,2012 , which claims the benefit of priority of European PatentApplication No. 11290390.1, filed Sep. 2, 2011, the subject matter ofboth of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention is directed to a castable refractory composition,to refractory linings and articles formed therefrom and to methods ofinstalling a refractory from said castable refractory composition.

BACKGROUND OF THE INVENTION

Refractories are materials having properties that make them suitable foruse as heat-resistant barriers in high temperature applications.Unshaped refractory materials have the ability to form a joint-lesslining, and are often referred to as monolithic. These materials areuseful for example as lining for cupolas hearth and siphon, blastfurnaces, main, secondary and tilting runners, and more generallyvessels or vessel spouts, ladles, tundishes, reaction chambers andtroughs that contain, direct the flow or are suitable to facilitate theindustrial treatment of liquid metals and slags, or any other hightemperature liquids, solids or gases. Unshaped refractories aretypically manufactured in powdered form and mixed with water prior toapplication. The wet material may be applied as a lining usingtechniques such as casting, spraying and gunning followed by setting anddrying, prior to firing.

An important aspect of any refractory material is its ability to bedried out safely and quickly after setting. As such, the wet materialshould have a high permeability to gas and especially water vapourduring dry-out on heating. Typically, therefore, some refractorymaterials, in particular those dedicated to thick and high thermalconductive linings (as for example carbon and/or SiC containingmonolithics) or applications that call for very fast liningcommissioning or installation in hot (i.e., 100-800° C.) conditions, areprepared using components which evolve inflammable hydrogen gas duringwetting and setting which produces pores, voids and micro-cracking,which in turn increases permeability to gas, and thus enables quickwater dry-out during heating. Typically, refractories are preparedincluding reactive metallic components which hydrolyse in the presenceof water and under specific pH to yield hydrogen gas.

However, the emission of hydrogen gas is a safety concern since there isa risk of accidental explosion of emitted hydrogen during setting whenmixed with oxygen from air in the presence of an ignition source. Itwould therefore be desirable to be able to prepare refractory materialswhich do not evolve hydrogen on setting.

However, owing to the absence of hydrogen and the expected concomitantdecrease in permeability to gas, there is a risk that any improvement insafety could be off-set by a reduction in the capability of therefractory lining to be dried out and heated up to service temperaturein a short time, or a detrimental effect on the ability to install therefractory under hot conditions on hot substrates. For example, with areduction in pores and voids through which water vapour would escapeduring dry-out, there is an increased risk of explosion resulting fromwater vapour pressure generation inside the lining during dry-out.

There is therefore a need for further castable refractory materialswhich do not emit significant amounts of hydrogen on setting and whichhave chemical, physical, mineralogical, thermal, commissioning and/orinstallation properties at least as good, or even improved compared to,conventional hydrogen emitting refractory materials. For example,commissioning should be easy and rapid, and installation should be asstraight forward as possible and not call for increased complexity suchas requiring the use of special liquids as colloidal suspensions, orother chemicals, such as phosphoric acids, phosphate solutions, sodiumsilicate and organic compounds suitable for polymerization, for wetmixing.

SUMMARY OF THE INVENTION

In accordance with a first aspect, there is provided a castablerefractory composition comprising:

-   -   5% to 95% by weight of alumina, aluminosilicate, or mixtures        thereof;    -   optionally up to 70% by weight silicon carbide,    -   optionally up to 10% by weight carbon,    -   0.1% to 5% by weight alkaline earth metal oxide and/or        hydroxide, and    -   0.1% to 5% by weight of silica having a surface area of at least        about 10 m²/g;    -   wherein the refractory composition includes no more than about        0.5% by weight of cementitious binder;    -   wherein the refractory composition does not release a        significant amount of hydrogen gas upon addition of water; and    -   wherein the refractory composition sets on addition of water

In accordance with a second aspect, there is provided an installablerefractory lining obtained by mixing the castable refractory compositionof the first aspect with 2% to 40% by weight water.

In accordance with a third aspect, there is provided a method ofinstalling the installable refractory lining of the second aspect of thepresent invention using a technique selected from casting, self flowing,shotcreeting, rodding, cast-vibrating, spraying, conventional drygunning or high density gunning, followed by setting and drying.

In accordance with a fourth aspect, there is provided an installedrefractory lining obtainable by the method of the third aspect. Thelining may be a lining for cupolas hearth and siphon, blast furnaces,main, secondary and tilting runners, vessels or vessel spouts, ladles,tundishes, reaction chambers and troughs that contain, direct the flowor are suitable to facilitate the industrial treatment of liquid metalsand slags, or any other high temperature liquids, solids or gases.

In accordance with a fifth aspect, there is provided a method ofinstalling a refractory comprising: mixing the castable refractorycomposition according to first aspect of the invention with water,forming the mixture into an article, allowing the article to set, anddrying the article to remove excess water.

In accordance with a sixth aspect, there is provided a refractoryarticle obtainable by the method of the fifth aspect of the presentinvention.

The present invention relates to a mixture suitable for use as arefractory, for example, as lining for cupolas hearth and siphon, blastfurnaces, main, secondary and tilting runners, and more generallyvessels or vessel spouts, ladles, tundishes, reaction chambers andtroughs that contain, direct the flow or are suitable to facilitate theindustrial treatment of liquid metals and slags, or any other hightemperature liquids, solids or gases. The mixture can also be used formanufacturing pre-shaped articles, in whole or part, for example,refractory bricks and crucibles. The mixture is characterized, in part,by the absence of significant gas emission and in particular inflammablehydrogen gas during its preparation, mixing with water, installation andsetting, which makes it particularly suitable for improving safety ofindustrial hardware where in the refractory is installed and used. Inparticular, the castable refractory composition of the present inventionsuppresses or prevents the reaction of metal particles, such asaluminium, via hydrolysis by the appropriate selection or omission ofmetallic or mineral additives. In spite of the absence of gas and inparticular hydrogen emission, the resulting refractory can be installedon hot substrates, and undergo quick and safe dry-out and heating. Therefractory is characterized, in part, by a high permeability to gas andwater vapour during dry-out, a high ratio of free water and a low ratioof water of hydration remaining after setting, and high mechanicalstrength after setting. The combination of such properties suppresses orprevents the formation of cracks, spalling or lining explosion duringdry-out and heating up to service temperature. Thus, linings formed fromthe castable refractory composition can be successfully used ininstallations normally calling for the use of hydrogen emittingrefractories or refractories installed after mixing with colloidalsuspensions or other chemicals such as phosphoric acid or phosphatesolutions, in order to fit with any installation calling for shortcommissioning time and safe dry-out.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic depiction of the measurement procedure formeasuring evolution of hydrogen gas from a wetted castable refractorycomposition.

FIG. 2 is a schematic depiction of a cross-section through an assemblyfor measuring gas permeability of cast samples.

DETAILED DESCRIPTON

In accordance with first aspect stated above, there is provided acastable refractory composition. By castable is meant the refractorycomposition is formable into a joint-less or unshaped product uponaddition of water, setting and drying to remove excess water.

The castable refractory composition comprises about 5-95% by weight ofalumina, aluminosilicate, or mixtures thereof, based on the total dryweight of the castable refractory composition. In an embodiment, thecastable refractory composition comprises about 30-95% by weight, forexample about, for example about 30-80% by weight, for example about30-70% by weight, for example about 40-70% by weight, for example about50-70% by weight, for example about 60-70% by weight of alumina or, forexample about 50-60% by weight of alumina, aluminosilicate, or mixturesthereof.

The alumina, aluminosilicate or mixtures thereof may comprise a materialselected from brown fused alumina, sintered alumina, white fusedalumina, calcined alumina, reactive or semi-reactive alumina, bauxite,fused or sintered mullite, andalusite and calcined chamotte having analumina content of about 30 to 75% by weight.

The alumina, aluminosilicate or mixtures thereof may comprise, consistessentially of, or consist of particles up to about 30 mm in size, asdetermined by an appropriately sized sieve. In embodiments, the alumina,aluminosilicate or mixtures thereof comprises, consists essentially of,or consists of particles up to about 10 mm, or up to about 6 mm, or upto about 4 mm, or up to about 2 mm, or up to about 1 mm in size.

In embodiments in which the castable refractory composition comprises upto about 15% by weight calcined alumina, based on the total dry weightof the castable refractory composition, the calcined alumina maycomprise particles having a d₅₀ of up to about 100 μm, for example, upto about 50 μm, or for example, between about 1 to about 10 μm. Calcinedalumina may be included as a component to adjust or enhance the flowcharacteristics of the castable once mixed with water. It may also beincluded to control and adjust the particle size distribution of theentire mix.

Unless otherwise stated, the mean (average) equivalent particle diameter(d₅₀ value) referred to herein is as measured in a well known manner bysedimentation of the particulate material in a fully dispersed conditionin an aqueous medium using a Sedigraph 5100 machine as supplied byMicromeritics Instruments Corporation, Norcross, Ga., USA (telephone: +1770 662 3620; web-site: www.micromeritics.com), referred to herein as a“Micromeritics Sedigraph 5100 unit”. Such a machine providesmeasurements and a plot of the cumulative percentage by weight ofparticles having a size, referred to in the art as the ‘equivalentspherical diameter’ (esd), less than given esd values. The mean particlesize d₅₀ is the value determined in this way of the particle esd atwhich there are 50% by weight of the particles which have an equivalentspherical diameter less than that d₅₀ value.

In embodiments in which the castable refractory composition comprises upto about 15% by weight reactive or semi reactive alumina, based on thetotal dry weight of the castable refractory composition, the reactive orsemi reactive may comprise particles having a maximum particle size ofup to about 50 μm, for example, up to about 25 μm or for example, a d₅₀between about 0.5 to 5 μm. Reactive or semi reactive alumina may beincluded as a component to adjust or enhance the flow characteristics ofthe castable once mixed with water. It may also be included to controland adjust the particle size distribution of the entire mix.

Advantageously, the castable refractory composition may comprise up toabout 70% by weight silicon carbide, for example about 5-70% by weightsilicon carbide, based on the total dry weight of the castablerefractory composition. In an embodiment, the castable refractorycomposition comprises about 10-50% by weight, for example about 10-40%by weight, for example about 15-40% by weight, for example about 20-40%,for example about 20-30% by weight silicon carbide.

The silicon carbide may comprise, consist essentially of, or consist ofparticles up to about 30 mm in size, as determined by an appropriatelysized sieve. In embodiments, the silicon carbide comprises, consistsessentially of, or consists of particles up to about 10 mm, or up toabout 8 mm, or up to about 6 mm, or up to about 4 mm, or up to about 2mm, or up to about 1 mm, or up to about 0.5 mm, or up to about 0.2 mm insize. In other embodiments, the silicon carbide comprises, consistsessentially of, or consists of particles having a d₅₀ up to about 300μm. The silicon carbide may comprise, consist essentially of, or consistof particles having a d₅₀ of up to about 200 μm, for example, up toabout 100 μm or, for example, a d₅₀ of up to about 60 μm.

Advantageously, the castable refractory composition may comprise up toabout 10% by weight, for example, about 1-10% by weight carbon, based onthe total dry weight of the castable refractory composition. In anembodiment, the castable refractory composition comprises about 1-5% byweight, for example about 1-4% by weight, for example about 2-3% byweight carbon. The carbon may comprise a material selected from carbonblack, graphite, coke, solid hydrocarbon having a carbon residue of atleast about 5% by weight after coking or a combination thereof. In anembodiment, the carbon comprises a mixture of graphite and carbon black.

The graphite may be mono-crystalline or polycrystalline (also known as“amorphous graphite”) and may comprise particles of up to about 1 mm insize, as determined by an appropriate sized sieve.

The carbon black may comprise particles having a d₅₀ of up to about 100μm, for example, up to about 75 μm of, for example, up to about 50 μm.The particles of carbon black may have a maximum specific surface areaof about 50 m²/g, as determined by nitrogen adsorption using the BETSpecific Surface Area measurement method, and a Loss on Ignition (LOI)at 1000° C. of at least 90% by weight.

The coke may comprise particles of up to about 2 mm in size, asdetermined by an appropriately sized sieve, and a LOI at 1000° C. of atleast 80% by weight.

The solid hydrocarbon may have a carbon residue of at least about 10% byweight after coking. It may be in a powdered form comprising particlesup to about 2 mm in size, as determined by an appropriately sized sieve,or it may be in the form of a coating of aggregates of 0.5 mm or more.Examples of solid hydrocarbons are bitumens, asphalts, phenolic basedresins and synthetic polymers or oligomers.

In an embodiment, the castable refractory composition comprises fromabout 5 to 70% by weight silicon carbide and from about 1 to 10% byweight carbon. In another embodiment, the castable refractorycomposition comprises from about 5 to 70% by weight silicon carbide andis substantially free of carbon. In a further embodiment, the castablerefractory composition comprises from about 1 to about 10% by weightcarbon and is substantially free of silicon carbide.

The castable refractory composition comprises about 0.1-5% by weightalkaline earth metal oxide and/or hydroxide, based on the total dryweight of the castable refractory composition. The alkaline earth metaloxide and/or hydroxide is a component of the binder on addition of waterand during setting. In an embodiment, the castable refractory comprisesabout 0.1-4% by weight alkaline earth metal oxide and/or hydroxide, forexample about 0.1-3% by weight alkaline earth metal oxide and/orhydroxide, for example about 0.1-2% by weight alkaline earth metal oxideand/or hydroxide, for example about 0.1-1.5% by weight or, for example,about 0.5-1.5% by weight alkaline earth metal oxide and/or hydroxide. Inan embodiment, the alkaline earth metal oxide and/or hydroxide is anoxide and/or hydroxide of magnesium, calcium or barium, or mixturesthereof. In an embodiment, the alkaline earth metal oxide and/orhydroxide is magnesia and/or magnesium hydroxide. In an embodiment, themagnesia comprises, consists essentially of, or consists of partiallyhydrated magnesium oxide. In another embodiment, the alkaline earthmetal oxide and/or hydroxide is calcium hydroxide and/or calcium oxide.In a further embodiment, the alkaline earth metal oxide and/or hydroxideis barium oxide and/or barium hydroxide. The alkaline earth metal oxideand/or hydroxide may comprise, consist essentially or consist ofparticles having a d₅₀ of less than about 100 μm, for example, a d₅₀ ofless than about 75 μm or, for example, a d₅₀ of less than about 50 μm.

The castable refractory composition comprises about 0.1-5% by weight ofsilica having a surface area of at least about 10 m²/g, as measured bynitrogen adsorption using the BET Specific Surface Area measurementmethod. In an embodiment, the castable refractory composition comprisesabout 0.1-4% by weight silica, for example about 0.1-3% by weightsilica, for example about 0.5-3% by weight silica or, for example, about1-3% by weight silica. The silica may have a surface are of at leastabout 20 m²/g, for example at least about 50, m²/g, for example at leastabout 100 m²/g or, for example at least about 200 m²/g. In anembodiment, the surface area of the silica is no more than about 500m²/g. In embodiment, the silica is selected from the group consisting offumed silica (also known as pyrogenic silica), silica fume (also knownas oxidized silicon vapour), microsilica, micro grinded silica andprecipitated silica. The silica having a surface area of at least about10 m²/g is a component of the binder, along with the alkaline earthmetal oxide or hydroxide and water.

The castable refractory composition includes no more than about 0.5% byweight cementitious binder, for example, no more than about 0.5 wt. %calcium aluminate cement and/or calcium silicate cement. In anembodiment, the castable refractory composition includes no more thanabout 0.25% by weight cementitious binder, for example, no more thanabout 0.25% by weight calcium aluminate cement and/or calcium silicatecement. In another embodiment, the castable refractory compositionincludes no more than about 0.1% by weight cementitious binder, forexample, no more than about 0.1% by weight calcium aluminate cementand/or calcium silicate cement. In another embodiment, the castablerefractory composition is substantially free of cementitious binder, forexample, substantially free of calcium aluminate cement and/or calciumsilicate cement.

In accordance with the first aspect, the refractory composition does notrelease a significant amount of hydrogen gas upon addition of water. By“does not release a significant amount of hydrogen gas upon addition ofwater” is meant that in accordance with the following measurementprocedure, the castable refractory composition directly following mixingwith water produces less than 25 cm³ of hydrogen gas per kilogram ofwetted castable refractory composition, i.e., hydrogen gas emission isless than about 25 cm³ H₂/kg of wetted castable refractory composition,for example, less than about 15 cm³ H₂/kg or, for example, less thanabout 10 cm³ H₂/kg of wetted castable refractory composition. In anembodiment, hydrogen emission is not detectable as measured inaccordance with the following procedure, described with reference toFIG. 1.

Directly after mixing with the castable refractory composition withwater, in accordance with EN 1402, approximately 300 g of the resultingwet product (2) is precisely weighed and placed into a sealablerecipient (4). The recipient (4) is sealed with a suitable sealing means(e.g., a rubber stopper) and is connected via a tube (8) to a vessel(10) and column (12) containing water (14). The water column (12, 14) iscontinuously weighed by suitable weighing means (16). The temperature is20° C. and the pressure is 1 atm and kept constant during the procedure.If hydrogen gas (18) is emitted, the gas (18) will displace water (14)from the column (12). The weight loss of the water column (12, 14) isused to calculate the cumulative hydrogen gas emission over a period of72 hours expressed in cm³ of hydrogen gas per kg of wetted castablerefractory composition.

The castable refractory composition sets upon addition of an appropriateamount of casting water. The appropriate amount of water will varydepending on the precise composition of the castable refractorycomposition, its intended use and the method by which the refractory isinstalled.

In an embodiment, between about 2% and about 40% water is added, basedon the total the dry weight of the castable refractory composition. Forexample, when the refractory is to be installed using a conventional drygunning technique, between about 10% and 40% by weight of water is addedto the castable refractory composition. For example, when the refractoryis to be installed using a casting or spray-casting technique, betweenabout 2 and about 8 wt. % water is added to the castable refractorycomposition. For example, when the refractory is to be installed using ahigh density gunning technique (as described in FR2798092 andFR2798091), between about 5 and about 20 wt. % water is added to thecastable refractory composition.

In embodiments, the castable refractory composition is mixed with about2-30% by weight of water, for example about 2-20% by weight of water,for example about 12-10% by weight of water for example about 5-30% byweight of water, for example about 10-30% by weight of water, forexample about 2-20% by weight of water, for example about 5-20% byweight of water, for example about 10-20% by weight of water, forexample about 2-10% by weight of water or, for example about 3-7% byweight of water, based on the total dry weight of the castablerefractory composition.

The castable refractory composition may further comprise from about 0.01to about 3% by weight solid powdered organic additive, for example, fromabout 0.05 to about 3% by weight or, for example, from about 0.05 toabout 2% by weight solid powdered organic additive. These additives maybe used as dispersants (e.g., to disperse fine or high specific surfacearea or hydrophobic components in water and, thus, enable the adjustmentof the flow of the castable with minimal water addition) or to adjustthe setting time and working time of the castable one mixed with water.The solid powdered additive may be selected from polyacrylates,polyglycols, polyglycolethers, carboxylic ethers, polymelamines,polynaphthalenes, ethers, citric acid, hydrated citric acid, citratesand mixtures thereof.

The castable refractory composition may further comprise from about 0.01to about 3% by weight solid soluble mineral additive, for example, fromabout 0.05 to about 3% by weight or, for example, from about 0.05 toabout 2% by weight solid soluble additive. These additives may be usedas dispersants (e.g., to disperse fine or high specific surface area orhydrophobic components in water and, thus, enable the adjustment of theflow of the castable with minimal water addition) or to adjust thesetting time and working time of the castable one mixed with water. Thesolid powdered additive may be selected from sodium phosphate, sodiumaluminate, boric acid, calcium silicate, calcium aluminate and mixturesthereof.

The castable refractory composition may further comprise up to about 5%by weight of metallic additives, based on the total dry weight of thecastable refractory composition. Metallic additives include aluminium,silicon, magnesium, iron, chromium, zirconium, their alloys and mixturesthereof. The metallic additive may be in powdered form. In anembodiment, the castable refractory composition comprises less thanabout 4% by weight, for example less than about 3% by weight, forexample less than about 2% by weight, for examples less than about 1% byweight, for example, less than about 0.75% by weight, for example, lessthan about 0.5% by weight or, for example, less than about 0.25% byweight of metallic additives. As noted below, in one embodiment, thecastable refractory composition is substantially free of metallicadditives.

Additives may be included in the castable refractory composition tosuppress or prevent oxidation of carbon. Thus, in an embodiment, thecastable refractory composition may comprise up to about 5% by weight ofan additive or additives which suppress or prevent oxidation of carbon,based on the total dry weight of the castable refractory composition. Inan embodiment, the additive is selected from the group consisting ofaluminium nitride, aluminium oxy-nitride, boron carbide, zirconiumcarbide, calcium carbide, metals that include aluminium, silicon,magnesium, iron, chromium, zirconium their alloys, and mixtures thereof.In an embodiment, the additive or additives which suppress or preventoxidation of carbon is not metallic. In another embodiment, the castablerefractory composition comprises no more than about 4% of said additiveor additives, for example, no more than about 3% by weight of saidadditive or additives, for example, no more than about 2% by weight ofsaid additive or additives or, for example, no more than about 1% byweight of said additive or additives.

If metallic additives are included which are sufficiently reactive togenerate a hydrolysis reaction upon addition of water, evolution ofhydrogen gas may be suppressed or prevented by preventing direct contactbetween water and metal particulates. Direct contact can be avoided bycoating the metal particulates with an impervious non-reacting material.The coating may be applied before addition of metal to the castablerefractory composition or in-situ during preparation of the castablerefractory composition.

The refractory castable composition may further comprise up to about1.0% by weight of organic fibres, based on the total dry weight of thecastable refractory composition. The organic fibres may improve thestrength of the composition during setting and drying and suppress oreliminate the appearance of cracks on drying. The organic fibres areeliminated during the firing of the refractory, which leads to thecreation of a network of small capillaries which may enhance theevacuation of water. In an embodiment, the refractory castablecomposition comprises up to about 0.8% by weight of organic fibres, forexample, up to about 0.5% by weight, for example up to about 0.3% byweight, for example up to about 0.2% by weight or, for example up toabout 0.1% by weight of organic fibres. In other embodiments, thecastable refractory composition comprises less than about 0.1% by weightof organic fibres, for example, less than about 0.05% by weight oforganic fibres. Organic fibres include polypropylene, polyacrylonitrileor polyvinylalcohol fibres, natural fibres derived from any suitablesource, such as coconuts, wood, grasses (e.g., sugarcane, bamboo)textile waste, cotton, hemp, flax or linen, and combinations thereof. Asnoted below, in one embodiment, the castable refractory composition issubstantially free of organic fibres.

As used herein, the term “substantially free” refers to the totalabsence of or near total absence of a specific compound or composition.For example, when a composition is said to be substantially free ofzirconia, there is either no zirconia in the composition or only traceamounts of zirconia in the composition. A person skilled in the art willunderstand that a trace amount is an amount which may be detectable butnot quantifiable and moreover, if present, would not adversely affectthe properties of the castable refractory composition or article formedtherefrom.

Thus, in further embodiments, the refractory composition issubstantially free of one or more of the following species:

-   -   (a) zirconia;    -   (b) zircon sand (zircon silicate)    -   (c) pitch;    -   (d) tar;    -   (e) hydraulically setting reactive alumina substantially free of        calcium oxide, known as “hydratable alumina” or ρ-alumina;    -   (f) spinel, prior to casting the refractory;    -   (g) andalousite;    -   (h) metallic additives, which in the presence of water are        capable of hydrolysing to form hydrogen gas; for example,        aluminium, silicon, magnesium and magnesium alloys; and    -   (i) organic fibres (as described above).

In further embodiments, the present invention does not utilise, relyupon or involve one or more of the following bonding systems:

-   -   (j) colloidal alumina suspensions and/or colloidal silica        suspensions used as liquid addition for preparation of an        installable product, permitting the stiffening and setting of        the castable mixture once installed by destabilisation of the        colloidal dispersion and gellification;    -   (k) acids such as phosphoric acid which react with oxides or        hydroxides such as magnesia and alumina or other impurities        leading to cross reticulation;    -   (l) sodium silicate, reacting either with acids (causing setting        by gellification of hydroxysilicates), salts (increasing        viscosity of silicate solution and gel formation) or alkaline        earth metal hydroxides (causing coagulation);    -   (m) aluminium phosphates hardening at a temperature greater than        100° C. or reacting at lower temperature with oxides such as        magnesia forming a bond by creation of a Mg and/or P hydrates        network;    -   (n) polysaccharide-based water soluble polymers;    -   (o) species which would cause the reticulation, polymerization        or co-polymerization of organic components, when present, which        are capable of being reticulated, polymerized or co-polymerized        in the presence of said species; and    -   (p) hydration of a reactive alumina substantially free of        calcium oxides known as hydratable alumina or ρ-alumina.

In accordance with the second aspect stated above, the present inventionis directed to an installable refractory lining obtained by mixing thecastable refractory composition described above in accordance with thefirst aspect with 2% to 40% by weight water. By “installable” is meantthat the refractory lining is of a form which is capable of beinginstalled by any of the methods described below.

In accordance with the third aspect stated above, the present inventionis directed to a method of installing the installable refractory liningof the second aspect of the present invention using a technique selectedfrom casting, self flowing, shotcreting, rodding, cast-vibrating,spraying, conventional dry gunning or high density gunning, followed bysetting and drying. These techniques are well known to persons ofordinary skill in the art.

In accordance with the second and third aspects of the presentinvention, the amount of casting water mixed with the castablerefractory composition will vary depending on the precise composition ofthe castable refractory composition, its intended use and the method bywhich the refractory is to be installed.

For example, when the refractory is to be installed using a conventionaldry gunning technique, between about 10% and 40% by weight of water isadded to the castable refractory composition.

For example, when the refractory is to be installed using a casting orspray-casting technique, between about 2 and 8 wt. % by water is addedto the castable refractory composition.

For example, when the refractory is to be installed using a high densitygunning technique, between about 5 and about 20 wt. % water is added tothe castable refractory composition.

In embodiments, the castable refractory composition is mixed with about2-30% by weight of water, for example about 2-20% by weight of water,for example about 2-10% by weight of water, for example about 5-30% byweight of water, for example about 10-30% by weight of water, forexample about 2-20% by weight of water, for example about 5-20% byweight of water, for example about 10-20% by weight of water, forexample about 2-10% by weight of water or, for example about 3-7% byweight of water, based on the total dry weight of the castablerefractory composition.

To achieve suitable wetting of the dry castable refractory compositionfor installation by casting, rodding, cast-vibrating, self-flowing orshotcreting, mixing times range from about 30 seconds to about 10 mins,for example, from about 30 seconds to about 5 mins or for example fromabout 30 seconds to about 2 mins. Suitable mixing apparatus are wellknown to persons of ordinary skill in the art.

In an embodiment, the setting step, during which the mixture hardens,includes reaction of alkaline earth metal oxide and/or hydroxide, silicahaving a surface area of at least 10 m²/g (for example, silica fume) andwater, without the need for firing.

Setting times range from about 1 hour to about 10 hours, for example,from about 2 hours to 8 hours, for example, from about 3 hours to 7hours, for example, from about 4 hours to 6 hours or, for example, fromabout 4 hours to 5 hours.

As described above, the mixture of castable refractory composition andwater may release less than about 25 cm³ of hydrogen gas per kilogram ofthe mixture, for example, less than about 15 cm³ H₂/kg of the mixtureor, for example, less than about 10 cm³ H₂/kg of the mixture. In anembodiment, hydrogen emission is not detectable by the measurementprocedure described herein.

Drying, to reduce or eliminate residual water, is conducted inaccordance with conventional procedures, as will be readily apparent toa person of ordinary skill in the art. Typically, drying is conducted inair at a temperature between about ambient e.g., about 20° C.) and 800°C. during installation.

Firing, i.e. heating the mixture at elevated temperature to produce aceramic/oxide bond, may be conducted at a temperature greater than about800° C., for example, equal to or greater than about 900° C., forexample, equal to or greater than about 1000° C., for example, equal toor greater than about 1100° C., or example, equal to or greater thanabout 1200° C., for example, equal to or greater than about 1300° C.,for example, equal to or greater than about 1400° C., for example, equalto or greater than about 1500° C. or, for example, equal to or greaterthan about 1600° C.

The viscosity of the mixture of castable refractory composition andwater may be adjusted by using the soluble powdered organic or solublemineral additives described above. Such additives, known as dispersingagents, serve to modify particulate surface properties either by directadsorption on the particulate surface or by modification of watersuspension ionic composition.

The mixture, if dedicated to placement by casting, cast-vibration,rodding, self-flowing or shotcreeting, after mixing may have a flow fromabout 50 to 200%, as determined in accordance with EN 1402. In anembodiment, the mixture has a flow from about 100 to 200%, for example,from about 100 to 150%. Thus, in another embodiment, the flow of themixture after mixing may be adjusted using the soluble powdered organicor soluble mineral additives described above.

The present invention is also directed to an installed factory liningobtainable by the method of the third aspect of the present invention.The lining may be a lining for cupolas hearth and siphon, blastfurnaces, main, secondary and tilting runners, vessels or vessel spouts,ladles, tundishes, reaction chambers and troughs that contain, directthe flow or are suitable to facilitate the industrial treatment ofliquid metals and slags, or any other high temperature liquids, solidsor gases.

In accordance with the fourth aspect stated above, the present inventionis directed to a method of installing a refractory comprising: mixingthe castable refractory composition according to first aspect of theinvention with water, forming the mixture into an article, allowing thearticle to set, drying the article to remove excess water, andoptionally firing the article at an elevated temperature, as describedabove.

As described above, the setting step includes reaction of alkaline earthmetal oxide and/or hydroxide, silica having a surface area of at least10 m²/g (for example, silica fume) and water, without the need forfiring.

In accordance with the sixth aspect stated above, the present inventionis directed to a refractory article obtainable by the method of thefifth aspect of the present invention. The refractory articles formedfrom the castable refractory composition are many and various andinclude, for example, pre-shaped articles, in whole or part, such asrefractory bricks and crucibles.

For the avoidance of doubt, the present application is directed to thesubject-matter described in the following numbered paragraphs:

1. A castable refractory composition comprising:

-   -   5% to 95% by weight of alumina, aluminosilicate, or mixtures        thereof,    -   optionally up to 70% by weight silicon carbide,    -   optionally up to 10% by weight carbon,    -   0.1% to 5% by weight alkaline earth metal oxide and/or        hydroxide, and    -   0.1% to 5% by weight of silica having a surface area of at least        about 10 m2/g;    -   wherein the refractory composition includes no more than 0.5% by        weight of cementitious binder;    -   wherein the refractory composition does not release a        significant amount of hydrogen gas upon addition of water; and    -   wherein the refractory compositions sets on addition of water.

2. A castable refractory composition according to paragraph 1, furthercomprising 0.01% to 3% by weight solid powdered organic additives.

3. A castable refractory composition according to paragraph 1 orparagraph 2, further comprising 0.01% to 3% by weight soluble mineraladditives.

4. A castable refractory composition according to any of the precedingnumbered paragraphs further comprising up to about 1% by weight ofmetallic additives.

5. A castable refractory composition according to any of the precedingnumbered paragraphs, further comprising up to about 5% by weight of anadditive or combination of additives which suppress or prevent theoxidation of carbon.

6. A castable refractory composition according to any of the precedingnumbered paragraphs, further comprising up to 0.5% by weight of organicfibers.

7. A castable refractory composition according to any of the precedingnumbered paragraphs, wherein the alumina, aluminosilicate or mixturethereof comprises a material selected from the group consisting of brownfused alumina, sintered alumina, white fused alumina, calcined alumina,reactive or semi-reactive alumina, bauxite, fused or sintered mullite,andalusite and calcined chamotte with alumina content of 30 to 75% byweight.

8. A castable refractory composition according to any of the precedingnumbered paragraphs, comprising 5% to 70% by weight silicon carbideand/or 1% to 10% carbon.

9. A castable refractory composition according to any of the precedingnumbered paragraphs, wherein the silicon carbide comprises particles upto about 30 mm in size.

10. A castable refractory composition according to any of the precedingnumbered paragraphs, wherein the carbon comprises a material selectedfrom carbon black, graphite, coke, solid hydrocarbon having a carbonresidue of at least about 5% by weight after coking, or a combinationthereof.

11. A castable refractory composition according to any of the precedingnumbered paragraphs, wherein the silica having a surface of at leastabout 10 m2/g is selected from the group consisting of fumed silica,silica fume, microsilica, micro grinded silica and precipitated silica.

12. A castable refractory composition according to any of the precedingnumbered paragraphs, wherein the alkaline earth metal oxide and/orhydroxide is an oxide and/or hydroxide of magnesium, calcium, barium ormixtures thereof.

13. A castable refractory composition according to any of the precedingnumbered paragraphs, wherein the composition comprise less than about0.5% by weight calcium aluminate cement and/or calcium silicate cement.

14. A castable refractory composition according to any of the precedingnumbered paragraphs, wherein the refractory composition is substantiallyfree of zirconia.

15. A castable refractory composition according to any of the precedingnumbered paragraphs, wherein the composition is substantially free ofspinel prior to casting the refractory.

16. A castable refractory composition according to any of the precedingnumbered paragraphs, wherein the composition is substantially free ofmetallic additives.

17. A castable refractory composition according to any of the precedingnumbered paragraphs, wherein the composition is substantially free oforganic fibres.

18. An installable refractory lining obtained by mixing the castablerefractory composition according to any of the preceding numberedparagraphs with 2% to 40% by weight water.

19. A method of installing the installable refractory lining ofparagraph 18 using a technique selected from casting, self-flowing, wetshotcreeting, rodding, cast-vibrating, spraying, conventional drygunning or high density gunning, followed by setting and drying.

20. The method of paragraph 19, wherein the setting step includesreaction of alkaline earth metal oxide and/or hydroxide, silica having asurface area of at least 10 m²/g and water, without the need for firing.

21. The method of paragraph 20, wherein the mixture releases less than10 cm³ of hydrogen gas per kg of wet castable refractory.

22. An installed factory lining obtainable by the method of any one ofparagraphs 19-21.

23. A method of installing a refractory comprising: mixing the castablerefractory composition according to any one of paragraphs 1-17 withwater, forming the mixture into an article, allowing the article to set,drying the article to remove excess water, and optionally firing thearticle.

24. A refractory article obtainable by the method of paragraph 23.

The invention will now be illustrated, by reference to the followingnon-limiting examples.

EXAMPLES Example 1

Four castables (A, B, C and D) were formulated and mixed with water.Compositions data is summarized in Table 1. These mixtures are suitablefor use as refractory lining for cupolas hearth and siphon, blastfurnaces main, secondary and tilting runners, vessels or vessel spouts,troughs that direct the flow of liquid metals and slags, or anyapplication calling for thick refractory linings and/or hot installationof linings and/or safe and quick dry-out and heating up.

The first mixture (A) is a typical ultra-low cement castable containingaluminium and silicon metal powder and, thus, generates hydrogen whenmixed with water. The second mixture (B) is the same as mixture A, savethat aluminium and silicon have been removed, and polypropylene fibresadded. This is an example of a cement based, non-hydrogen releasingcastable. The third and fourth mixtures (C & D) are cement-free andnon-hydrogen releasing castables prepared in accordance with the presentinvention.

The dispersion and setting time modification solid powdered organic andsoluble mineral additions were adjusted to provide similar flow andsetting time, as given in Table 2, for both bonding systems used.

TABLE 1 Weight % composition Mixture A Mixture B Mixture C Mixture DBrown fused alumina (0 56 56 56 56 to 6 mm) Silicon Carbide (0 to 25 2525 25 2 mm) Carbon black 1.1 1.1 1.1 1.1 Solid hydrocarbon 1.5 1.5 1.51.5 Calcined and reactive 11.45 12.7 13.3 13.3 alumina 70% Al₂O₃ calcium1.5 1.5 none none aluminates cement Silica fume 2 2 2 2 Aluminium powder0.3 none none none Silicon powder 1 none none none solid powderedorganic 0.15 0.15 0.25 0.25 and soluble mineral additives Ca(OH)₂ 0 00.8 0 MgO 0 0 0 0.8 Polypropylene fibres none 0.05 0.05 0.05 Total ofdry components 100 100 100 100 Casting water added 4.5 4.5 4.5 4.5

Gas permeability was measured on samples cored out of larger castedpieces preliminary treated at the temperatures give in Table 2, both inparallel and perpendicular direction compared to the casting direction.The procedure described in the European standard (EN 993-4) nor the onedescribed in the American standard (ASTM C577) are not suitable for themeasurement of the permeability of refractory castables, unless thecastables are fired and have a permeability higher than 0.05×10⁻¹³m².Therefore, the following procedure was used. Assemblies were derivedfrom those used for civil engineering concretes. The developed set up(FIG. 2) is rather similar. FIG. 2 is a cross-section through theassembly. The assembly (1) comprises sample support members (3) whichare held together by suitable fixing means (5), e.g., a pair of bolts.Axial flat rubber rings (7), pressed at 10 N.m over the ground surfacesof the cylindrical sample (9) leave a flow section having a diameter of45 mm. The sample is coated with polyester resin (11) prior to testing.The assembly further comprises rubber O-rings (13). Four capillaryflow-meters (not shown) were used to measure the very small flow goingthrough the castables samples (9), with measurement ranges from 0.1 to100 cm³/min. Rotameters (not shown) were used for higher flow rates.

The flow rate of a mixture of nitrogen and oxygen (80% N₂-20% O₂) wasmeasured in the steady state for different pressure drops (inputpressure between 0.25 and 0.6 MPa, output pressure 0.1 MPa, thickness ofthe sample 30 mm) to check for the flow regime (slip flow, viscous flowor visco-inertial flow). The direction of flow of gas mixture throughthe assembly and castable sample is indicated in FIG. 2 by the dashedarrow. The relationship between the pressure drop and the measured flowrates was first checked to verify that it can be considered as linear(→viscous flow regime). A permeability value may thus be calculated fromthe slope according to the Darcy law. These Darcian permeability valuesare the ones given in Table 2.

Hydrogen evolution was measured in accordance with the method describedabove.

The two formulations based on ultra low cement bond (A & B) andformulations C & D, illustrating the present invention, exhibit similarwetting time, flow and setting time. This illustrates the capability ofthe compositions of the present invention to be mixed and installed bythe cast-vibration method using same equipment, same procedures and withsame easiness as ultra low cement bond formulations.

Formulation A, due to the increase of pH resulting from calciumaluminates cement dissolution, exhibits hydrogen emission resulting froma hydrolysis reaction between the metal powders and water. FormulationsB, C and D which do not contain metal powder, do not release detectableamounts of hydrogen.

In formulation A, the release of hydrogen during setting produces pores,voids and micro-cracking. As explained above, this well-known mechanismserves to increase permeability to gas and, thus, facilitates quickwater dry-out during the heating up phase or safe installation on hotsubstrates.

In formulation B, illustrating an ultra low cement castable wherepermeability is enhanced by the percolated capillary network resultingfrom polypropylene fibres

TABLE 2 Mixture A Mixture B Mixture C Mixture D Mixing time needed forachieving 1:10 1:05 1:15 1:10 wetting of dry mixture [min:s] Flow aftermixing (as per EN 1402) 138 143 136 139 [%] Setting time [h:min] 4:304:40 4:30 4:20 Cumulative Gas (hydrogen) 3200 Not Not Not emission 72hours after casting measurable measurable measurable [cm³/kg ofcastable] (<10) (<10) (<10) Modulus of rupture after drying at 5.3 3.55.6 6.5 110° C. (as per EN 1402) [Mpa] Cold crushing strength afterdrying at 33 15 39 47 110° C. (as per EN 1402) [Mpa] Modulus of ruptureafter after 4.7 3.4 6.2 7.5 treatment at 200° C. (as per EN 1402) [Mpa]Cold crushing strength after 33 19 43 51 treatment at 200° C. (as per EN1402) [Mpa] Gas (air) permeability in direction 4.5 2.6 15.2 14.7parallel to casting direction after drying at 110° C. [×10⁻¹⁶ m²] Gas(air) permeability in direction 8.8 2.7 290 340 perpendicular to castingdirection after drying at 110° C. [×10⁻¹⁶ m²] Gas (air) permeability indirection 7.3 28.3 39.6 42.5 parallel to casting direction after dryingat 200° C. [×10⁻¹⁶ m²] Gas (air) permeability in direction 10.6 26.5 468551 perpendicular to casting direction after drying at 200° C. [×10⁻¹⁶m²]burnout, it is visible that (1) permeability after treatment at 110° C.is significantly lower than for castable A, and (2) permeabilityincreases only after melting of the fibres. Even if the permeability offormulation B can be increased by melting the fibres, the resultingincrease in permeability occurs at a temperature (>160° C.) at whichmost of the water contained in the castable has already turned intovapour and, thus, too late to permit easy and safe water dry-out.

In formulations C and D, the bond system leads, surprisingly, to aparticularly high gas permeability, even after treatment at 110° C.,which illustrates the capability of the castable refractory compositionto be quickly and safely dried out. Formulation C and D also exhibitshigher mechanical strength than formulations A and B. This particularproperty, associated with the high gas permeability, will enable liningsin accordance with the present invention to be dried out quicker withless risk of steam spalling or lining explosion. Further, the absence ofhydrogen emission, makes the composition of the present invention saferto use compared to conventional ultra low based castables, especially interms of decreased risk of explosion resulting either (1) from watervapour pressure generation inside lining during dry out (that couldexceed the ultimate strength of the lining), or (2) from detonation ofhydrogen emitted during setting when mixed with oxygen from air andsubmitted to accidental ignition source.

Example 2

Ten castables were formulated and mixed with water. Compositional datais summarized in Table 3. The dispersion and setting time modificationorganic and soluble mineral additions were adjusted to provide similarflow and setting time, as given in Table 4, for both bonding systemsused.

In formulations 2, 3, 6 and 8 containing cement and metallic aluminium,the hydrolysis reaction takes place and leads to the generation ofhydrogen. This hydrogen release during the setting step of the castableleads to an increase of the permeability to gas, which is a governingfactor in the capability of the castable to be dried and heated up quickand safe. The phenomenon is the same in the two tested cement bonds (lowcement and ultra low cement). The presence of polypropylene fibres inthe cement bonded samples (mixtures n° 2 & 6) releasing hydrogen doesnot influence the gas permeability measured after treatment at 110° C.The presence of the same fibres in cement bonded castable not releasinghydrogen (mixtures n° 1 & 5) does not increase permeability to a levelcomparable to versions releasing hydrogen as the temperature of 110° C.is too low to achieve melting of the fibres and creation of aninterconnected capillary network (which would be expected to lead to anincrease in permeability). In both cement based bonds tested (low andultra-low cement content) the presence of fibres does not thereforeincrease the capability of castables to be safely and quickly dried out.

Mixtures 9 and 10, illustrating the present invention, can be mixed andinstalled by cast-vibration method using same equipment, same proceduresand with same easiness as the other cement based compositions. Mixtures9 and 10 do not contain fibres nor release any gas during setting, butnevertheless exhibit a permeability of the same order of magnitude thanhydrogen releasing mixtures. This property enables linings based on theinvention to be dried out more quickly with less risk of steam spallingor lining explosion. This capability, associated with the absence ofhydrogen emission, makes the castables of the present invention safer touse than conventional low or ultra low cement based castables.

TABLE 3 Mixture 1 Mixture 2 Mixture 3 Mixture 4 Mixture 5 Mixture 6Mixture 7 Mixture 8 Mixture 9 Mixture 10 Mixture description Bond typeLow Low Low Low Ultra Low Ultra Low Ultra Low Ultra Low Present PresentCement Cement Cement Cement Cement Cement Cement Cement inventioninvention Drying fibres y y n n y y n n N N Hydrogen release n y y n n yn y N N Mixture weight composition [%] 60% alumina chamotte 80 80 80 8080 80 80 80 80 80 0 to 6 mm Graphite 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.51.5 Carbon black 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Calcined andreactive 7.29 6.89 6.94 7.34 13.79 13.39 13.84 13.44 13.45 13.45 alumina70% Al₂O₃ 5 5 5 5 1.5 1.5 1.5 1.5 0 0 calcium aluminates cement Silicafume 4.5 4.5 4.5 4.5 1.5 1.5 1.5 1.5 2 2 Aluminium powder 0 0.4 0.4 0 00.4 0 0.4 0 0 Solid powdered organic and 0.16 0.16 0.16 0.16 0.16 0.160.16 0.16 0.25 0.25 soluble mineral additives Polypropylene fibres 0.050.05 0 0 0.05 0.05 0 0 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 0 1.3 0 MgO 0 0 0 0 0 00 0 0 1.3 Casting water added 6.1 6.1 6.1 6.1 6.1 6.1 6.1 6.1 6.1 6.1

TABLE 4 Mixture 1 Mixture 2 Mixture 3 Mixture 4 Mixture 5 Mixture 6Mixture 7 Mixture 8 Mixture 9 Mixture 10 Flow after mixing 150 150 165177 134 140 155 147 141 150 (as per EN 1402) [%] Cumulative Gas Not 34203630 Not Not 3160 Not 3390 Not Not (hydrogen) meas- measurablemeasurable measurable measurable measurable emission 72 hours urable(<10) (<10) (<10) (<10) (<10) after casting (<10) [cm³/kg of castable]Gas (air) 2.5 24.5 25.0 0.3 2.5 40.1 2.2 38.9 37.2 42.3 permeability indirection parallel to casting direction after drying at 110° C. [×10⁻¹⁶m²]

The invention claimed is:
 1. A castable refractory compositioncomprising: from 5% to 95% by weight of alumina, aluminosilicate, ormixtures thereof; silicon carbide in an amount up to 70% by weight;carbon in an amount up to 10% by weight; from 0.1% to 5% by weightalkaline earth metal oxide and/or hydroxide; and from 0.1% to 5% byweight of silica having a surface area of at least about 10 m²/g,wherein the refractory composition comprises no more than 0.5% by weightof cementitious binder, wherein the refractory composition releases lessthan 25 cm³ of hydrogen gas per kilogram of wetted castable refractorycomposition, and wherein the refractory compositions sets on addition ofwater.
 2. A castable refractory composition according to claim 1,further comprising up to about 1% by weight of metallic additives.
 3. Acastable refractory composition according to claim 1, further comprisingup to about 5% by weight of an additive or combination of additives,which suppress or prevent the oxidation of carbon.
 4. A castablerefractory composition according to claim 1, further comprising up to0.5% by weight of organic fibers.
 5. A castable refractory compositionaccording to claim 1, wherein the alumina, aluminosilicate or mixturesthereof comprise a material selected from the group consisting of brownfused alumina, sintered alumina, white fused alumina, calcined alumina,reactive or semi-reactive alumina, bauxite, fused or sintered mullite,andalusite and calcined chamotte with alumina content ranging from 30 to75% by weight.
 6. A castable refractory composition according to claim1, comprising from 5% to 70% by weight silicon carbide and/or from 1% to10% by weight carbon.
 7. A castable refractory composition according toclaim 1, wherein the silicon carbide comprises particles up to about 30mm in size.
 8. A castable refractory composition according to claim 1,wherein the carbon comprises a material selected from carbon black,graphite, coke, solid hydrocarbon having a carbon residue of at leastabout 5% by weight after coking, or a combination thereof.
 9. A castablerefractory composition according to claim 1, wherein the silica having asurface of at least about 10 m²/g is selected from the group consistingof fumed silica, silica fume, microsilica, micro grinded silica, andprecipitated silica.
 10. A castable refractory composition according toclaim 1, wherein the alkaline earth metal oxide and/or hydroxide is anoxide and/or hydroxide of magnesium, calcium, barium, or mixturesthereof.
 11. A castable refractory composition according to claim 1,wherein the composition comprise less than about 0.5% by weight calciumaluminate cement and/or calcium silicate cement.
 12. An installablerefractory lining obtained by mixing the castable refractory compositionaccording to claim 1 with from 2% to 40% by weight water.
 13. A methodof installing the installable refractory lining of claim 12, the methodcomprising at least one of casting, self-flowing, wet shotcreeting,rodding, cast-vibrating, spraying, conventional dry gunning, or highdensity gunning the castable refractory composition; and setting anddrying the castable refractory composition to form the refractorylining.
 14. The method of claim 13, wherein the setting comprisesreaction of the alkaline earth metal oxide and/or hydroxide, silicahaving a surface area of at least 10 m²/g, and water, without firing thecastable refractory composition.
 15. The method of claim 14, wherein themixture releases less than 10 cm³ of hydrogen gas per kilogram of wetcastable refractory.
 16. An installed factory lining obtained by themethod of claim
 13. 17. A method of installing a refractory comprising:mixing the castable refractory composition according to claim 1 withwater; forming the mixture into an article; allowing the article to set;and drying the article to remove excess water.
 18. The method of claim17, further comprising firing the article.
 19. A refractory articleobtained by the method of claim
 17. 20. The castable refractory compoundof claim 1, comprising silicon carbide in an amount between 15-40% byweight.